BIND 10 #2209: define and implement ConfigurableClientList::getCacheZoneUpdater()

[BIND 10 Development]

#2209: define and implement ConfigurableClientList::getCacheZoneUpdater()
-------------------------------------+-------------------------------------
            Reporter:  jinmei        |                        Owner:
                Type:  task          |                       Status:  new
            Priority:  medium        |                    Milestone:  Next-
           Component:  data source   |  Sprint-Proposed
           Sensitive:  0             |                     Keywords:
         Sub-Project:  DNS           |              Defect Severity:  N/A
Estimated Difficulty:  0             |  Feature Depending on Ticket:
         Total Hours:  0             |  background zone loading
                                     |          Add Hours to Ticket:  0
                                     |                    Internal?:  0
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 A subtask of #2201, depend on #2206, #2207.

 This is a new method to `ConfigurableClientList` and will eventually
 replace reload().  conceptually it would look this:

 {{{#!cpp
 shared_ptr<memory::ZoneUpdater>
 ConfigurableClientList::getCacheZoneUpdater(config) {
     // identify the in-memory client
     if (type == "MasterFiles") {
         updater = mem_client->ztable_segment->getZoneUpdater(
             config,
             boost::bind(loadMemoryZoneFromFile, master_file, _1),
             boost::bind(&InMemoryClient::installZone, mem_client, _1));
         return (updater);
     } else {
         updater = mem_client->ztable_segment->getZoneUpdater(
             config,
             boost::bind(loadMemoryZoneFromDataSource, backend_client, _1),
             boost::bind(&InMemoryClient::installZone, mem_client, _1));
         return (updater);

     }
 }

 void
 loadMemoryZoneFromFile(ZoneData* zone_data, string zone_file) {
     // fill in zone_data from zone_file
 }

 void
 loadMemoryZoneFromDataSource(ZoneData* zone_data, DataSourceClient*
 backend) {
     // fill in zone_data using backends' iterator
 }
 }}}

 We should already have something close to the two load_action
 callbacks.  We should only have to adjust the interface.

 installZone would reset the corresponding zone segment for shared
 memory version.  For the moment that could be an empty functor object.

-- 
Ticket URL: <http://bind10.isc.org/ticket/2209>
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BIND 10 Development